This invention relates to means and methods for controlling towed airborne vehicles and for the use of such vehicles in assessing the damage created by the explosion of a bomb, a missile, or similar traveling explosive device.
Towed airborne vehicles, such as bomb damage assessment devices, are well known. Towed damage assessment vehicles are towed behind a bomb, and use a video camera to view the area of the bomb explosion. The vehicle in which the video camera is located is mounted in or on the bomb, released during flight of the bomb, and is towed by the bomb at a distance behind it so that the camera can take pictures of the explosion site for a period of time after the explosion occurs and before the camera is destroyed.
This enables personnel viewing the video pictures to determine whether the bomb has hit the desired target, and the extent of the damage done.
In prior devices of this type, the tether line for towing the vehicle is wound on a reel mounted in or on the bomb. The vehicle is deployed by use of an explosive device, and the tether unwinds from the reel. The unwinding speed is controlled by a centrifugal brake.
Various problems have been experienced with such prior bomb damage assessment devices. First, the length of the tether is relatively short so that the viewing time after the explosion is limited.
Accordingly, it is an object of the present invention to produce a damage assessment device and method in which the explosion site viewing time is substantially greater than in the past.
Another problem with such prior devices is that shock forces upon release of the towed vehicle and upon stopping the dispensing of the tether line tend to be relatively large. This puts relatively great stress on the tether.
Accordingly, it is another object of the invention to provide a damage assessment device and method in which the shock forces and the tether line diameter are minimized.
Another problem with such prior devices is that the tether dispensing equipment used is relatively large, heavy, and costly.
Accordingly, it is another object of the present invention to provide a damage assessment device and method in which the assessment vehicle is relatively small, lightweight and inexpensive to manufacture.
It is a further object of the invention to provide a damage assessment device and method having the foregoing desirable attributes which does not require excessive electrical power to operate, and which is relatively resistant or impervious to electromagnetic interference signals.
An additional object of the invention is to provide a device of the type described above which can be used with a minimum of modification of the bomb, missile or other xe2x80x9cmother craftxe2x80x9d in or on which the vehicle is carried.
The problems of controlling a towed airborne vehicle such as a decoy or target towed behind an airplane also are addressed by the present invention. Accordingly, it also is an object of the invention to provide means for improving the deployment and flight of such vehicles.
Special problems are caused by the need to recover towed vehicles, especially when they are expensive to replace. Again, the space available for recovery equipment is limited.
When the mother craft towing the vehicle is a jet or rocket-propelled craft, there is the problem that the tether cord can be burned by the jet or rocket exhaust, if the aircraft turns. This often requires the aircraft to be modified or other expensive measures taken to ensure the freedom to maneuver the aircraft without loss of the towed vehicle.
Accordingly, it is an object of the invention to provide compact means for deploying and recovering towed vehicles, and preventing either the loss of the towed vehicle or the maneuverability of the mother craft due to burning of the tether cord.
In accordance with the present invention, the foregoing objects are satisfied by the provision of a towed vehicle control and damage assessment device and method in which an electrically-operated brake is used to stop the dispensing of tether cord gradually, so as to minimize shock. Also, the dispensing of tether cord can be stopped and started easily so as to allow greater control over the movement of the towed vehicle.
Tether line or cord preferably is wound on an elongated spool and is dispensed longitudinally over one end flange of the spool. The tether line drives a relatively light-weight rotor while the wound pack of cord remains stationary. This reduces the mass of the rotating body and facilitates braking with a small, lower-power brake, and facilitates using a longer tether line without adding excessively to the vehicle size and braking load.
Preferably, the braking force provided by the brake greatly multiplied by use of a curved conduit, preferably a sinuous conduit, as a cord guide, with the tether line bent around the curve(s) of the conduit so as to minimize the electrical power required by the brake to do its work. Also, the curved conduit can be used as a friction brake to slow the dispensing of the tether cord.
The shock force on the tether line created by the initial release of the towed vehicle is reduced by a selected one of or combination of methods, including reducing the explosive charge used to project the vehicle from the xe2x80x9cmother craftxe2x80x9d, that is, the bomb, missile or aircraft, and/or deploying a ribbon streamer or a small parachute or other drag-increasing means from the vehicle to pull it out of the mother craft at a more gradual rate than that provided by explosive propulsion.
In one embodiment of the invention, the size and weight of the towed vehicle can be reduced by embedding electrical power wires in the tether line, either alone or with a fiber-optic cable for supplying communication signals. Provision of the wires eliminates the need for an on-board battery, or reduces the size and weight of the battery needed. The fiber-optic cable allows the transmission of command signals from the computer in the mother craft to the towed vehicle without enemy xe2x80x9cjammingxe2x80x9d or other interference.
Recovery means are provided for recovering a towed vehicle. A winch is mounted in the mother craft to pull the vehicle into the craft after deployment and use of the towed vehicle. Thus, the dispensing mechanism and brake within the towed vehicle are used for deployment and the winch is used for retrieval. This minimizes the weight of and electrical power needed in the towed vehicle, and makes it unnecessary to cut the vehicle loose and lose it when its task is finished.
Advantageously, because the dispensing is done by a mechanism within the towed vehicle, the anchor point for the tether line can be fixed on the mother craft. Thus, a fire-resistant covering can be used to protect a relatively short portion of the tether line from being burned by the hot engine exhausts(s) of the mother craft""s engine(s) when the mother craft turns. The distance to which the towed craft is towed is completely unrestricted by the use of such a covering.
The foregoing and other objects and advantages of the invention will be apparent from or set forth in the following description and drawings.